Rehabilitation is a required but difficult process for patients trying to recover the full control of their hips, knees, or other parts of their body. Some of the most important types of rehabilitation include neuromuscular rehabilitation for neurally impaired patients due to spinal cord injury and muscle or ligament rehabilitation for patients with one or more of hip, knee, or ankle replacement surgeries. The spinal cord is capable of relearning the ability to walk through proper training even when cut off from the brain. See I. Wickelgren, “Teaching the spinal cord to walk,” Science, 279:319–21 (1998); C. Wang, J. Bobrow, and D. Reinkensmeyer, “Dynamic motion planning for the design of robotic gait rehabilitation,” Journal of Biomechanical Engineering, Transactions of the ASME, 127:672–79 (2005). A large proportion of people with spinal cord injury who sustain motor incomplete lesions can regain some recovery in their walking ability. Symmetrical movements of lower extremities consistent with normal physiological gait patterns provide some of the critical sensory cues necessary for maintaining and enhancing walking ability. See A. Behrman and S. Harkema, “Locomotor training after human spinal cord injury: a series of case studies,” Physical Therapy, 80(7):688–700 (2000).
Although procedures such as hip replacement surgery can be very beneficial, the best way to maximize those benefits is through proper rehabilitation. The American Academy of Physical Medicine and Rehabilitation (AAPMR) reports that, as Baby Boomers age, the number of total hip replacements is expected to increase by more than 60 percent in the next 30 years. Physical therapy is extremely important in the overall outcome of any joint-replacement surgery. The goals of physical therapy are to prevent contractures, improve patient education, and strengthen muscles through controlled exercises. Contractures result from scarring of the tissues around the joint. Contractures do not permit full range of motion and, therefore, impede mobility of the replaced joint.
A promising solution for assisting patients with spinal cord injury, those with joint replacement surgery, and many other mobility-impaired patients during rehabilitation is to design exoskeletal devices. It has already been shown that motorized robotic-assisted devices can be very helpful in training individuals to regain their walking ability following motor incomplete spinal cord injury. See T. Hornby, D. Zemon, and D. Campbell, “Robotic-assisted, body-weight-supported treadmill training in individuals following motor incomplete spinal cord injury,” Physical Therapy, 85(1):52–66 (2005). Exoskeletal devices have the potential to be used during the sitting, standing, and walking stages of rehabilitation. But such a versatile device is not currently available.
In view of the shortcomings of the known approaches, there is an apparent need for an improved exoskeletal device for patients requiring rehabilitation. It is therefore an object of the present invention to provide a modular exoskeletal device that permits components to be added as rehabilitation progresses through the sitting, standing, and walking stages. Thus, for example, only two actuators are provided during the standing stage while four actuators are provided during the walking stage. An additional object is to provide stationary control and computing software and hardware so that the patient need not carry this extra load. A related object is to provide an exoskeletal device offering reduced weight and power requirements tailored to meet the specific needs of a patient during each stage of rehabilitation. Another object is to maintain the torso of the patient in a stable position without effort from the patient.
Additional objects and advantages of this invention will be apparent from the following detailed description.